Anyone who has watched Sex and the City can tell you that muscular men have some obvious evolutionary advantages. But the study described in this New Scientist story suggests that in some respects, the 98-pound weaklings among us have an evolutionary edge.

Evolutionary biologist William Lassek crunched data on the muscularity, sex lives, caloric intake, and biochemistry of 5,500-plus men and tried to figure the benefits and costs of being all pumped up. The benefits, of course, include more sex and (though it matters less these days than it used to) the upper hand in potentially violent physical confrontations. But bigger muscles also lead to poor immune systems (because of higher testosterone levels) and the need to procure more food. Lassek argues that these costs offset the skinny male’s relative lack of mating opportunities — and explain his place in the gene pool.